>>salary is the lowest amount you can offer while still enticing people to work for you
>> business is not charity
And this is why unions exist. Even if managers try to be nice, even if the company gives out buckets of benefits and pays a living wage, this is the adversarial thought that exists in business currently. Management wants to pay the lowest they can, because that helps the business the most. They want to spend the least amount possible because that's the correct business choice.
Management/Ownership and Employees are frequently at odds when it comes to their goals, and changing the math from "me vs the company" to "the union vs the company" is a huge boon for employees.